When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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Monday, March 3, 2014

by Joe Romm, Climate Progress, March 3, 2014In an unprecedented move, the President’s Science Advisor, Dr. John P. Holdren, has published a devastating 6-page debunking of one of the country’s leading climate confusionists, Roger Pielke, Jr.

I’ll excerpt Holdren’s comprehensive critique, “Drought and Global
Climate Change,” below. Worsening drought may be the climate impact that
affects the most people in the coming decades, as I discussed in my
2011 literature review in the journal Nature. It is valuable to see the the subject laid out so clearly by the nation’s top scientist.

Our understanding of drought and climate change is evolving pretty
rapidly, so even the latest IPCC reports are already out of date. Having
read much of the recent drought literature and interviewed many of the
leading drought experts in the last few years, I can say that Holdren’s
views are right in the mainstream of climatologists’ view of drought. I
can think of no climate scientists who share Pielke’s startling
assessment of Holdren’s views as “zombie science.”

In fact, some drought experts believe the situation is considerably
worse than is widely understood. As one top researcher on the
climate-drought link confirmed with me recently, “The U.S. may never again return to the relatively wet conditions experienced from 1977 to 1999.”

HOLDREN AND PIELKE

John Holdren is one of the most distinguished scientists in America. He
is a past president of the American Association for the Advancement of
Science. Author of over 200 articles and papers, Holdren is a member of
the National Academy of Sciences, the National Academy of Engineering,
and a foreign member of the U.K.’s Royal Society.

I have known Holdren for more than two decades, and not only does he
have more breadth of knowledge on all things climate than most, he is
very judicious in his choice of words.

Roger Pielke, Jr., is a political scientist who has publicly questioned
the scientific integrity of more climate scientists than just about
anyone else on the planet. He has smeared literally hundreds of
scientists (as I document here).

That is no doubt a key reason Pielke was included on Foreign Policy‘s “Guide to Climate Skeptics.”
No doubt that’s why the websites that most prominently feature or
reprint Pielke’s attacks are climate denial sites like WattsUpWithThat
and ClimateDepot. It is also why he is probably the single most disputed
and debunked person in the science blogosphere, especially on the
subject of extreme weather and climate change (see here and here).

Tim Lambert (Deltoid) has a whole category
on Pielke: “Roger Pielke Jr has attempted to trash me using innuendo,
fabrication and outright misrepresentation. I correct the record.”

Before his death, the widely revered climatologist Stephen Schneider described one of his run-ins with Pielke this way five years ago:

It is typical of a trickster and a
careerist – which is how I personally see him – and so do most of my
colleagues these days who I have discussed it with.

Now Pielke has embraced the widely discredited
Bjorn Lomborg argument that climate action is bad for the poor, when
the science makes clear that climate inaction would be devastating to
the poor. Climate action is the only sustainable path out of poverty, as
climate expert and development practitioner John Abraham explains in a UK Guardian piece that Pielke has yet to respond to.

It should be obvious that if you’ve garnered a 6-page debunking by
the nation’s top scientist, then you’ve moved into the elite ranks of
climate confusionists.

If you want the full story on how Pielke has attempted to scandalize
his personal quibbles with Holdren (to use a phrase Dr. Stefan Rahmstorf
first applied to Pielke), HotWhopper has a must read post. Here’s the short version.

Back in December, Pielke criticized Holdren for pulling his punches on climate science, tweeting, “Since becoming sci advisor Holdren has always stayed on safe (boring) ground in his public remarks.”

Then, in mid-February, when Holdren offered some straightforward
well-grounded scientific statements about how climate change is
worsening Western droughts, Pielke slammed him, tweeting “it is brazen for zombie science to show up in the White House!”

Talk about damned if you do and damned if you don’t!

As Holdren explains, in a February 25 hearing, “Senator Jeff Sessions
(R-AL) suggested that I had misled the American people with comments I
made to reporters on February 13.” In particular, Sessions quoted
testimony Pielke had given in July:

It is misleading, and just plain incorrect, to claim that
disasters associated with hurricanes, tornadoes, floods or droughts
have increased on climate timescales either in the United States or
globally.

Drought has “for the most part, become shorter, less, frequent, and
cover a smaller portion of the U.S. over the last century”. Globally,
“there has been little change in drought over the past 60 years.”

As an important aside, Sheffield’s paper has been disputed. I
recently interviewed Aiguo Dai, and he thinks the Sheffield analysis is
flawed. Dai stands by his conclusion in a 2012 paper in Nature Climate Change
that “Historical records of precipitation, streamflow, and drought
indices all show increased aridity since 1950 over many land areas.”

When Holdren rebutted Pielke’s charges in Senate testimony, Pielke
demanded “If you do indeed believe that my views are ‘outside the
scientific mainstream’ could you substantiate that claim”? Holdren’s full devastating reply is “Drought and Global Climate Change: An Analysis of Statements by Roger Pielke Jr.”Besides reviewing the drought literature, Holdren makes a crucial
point that “any reference to the CCSP 2008 report in this context should
include not just the sentence highlighted in Dr. Pielke’s testimony but
also the sentence that follows immediately in the relevant passage from
that document and which relates specifically to the American West.”
Here are the two key sentences from the report in their entirety):

Similarly, long-term trends (1925–2003) of hydrologic
droughts based on model derived soil moisture and runoff show that
droughts have, for the most part, become shorter, less frequent, and
cover a smaller portion of the U.S. over the last century (Andreadis &
Lettenmaier, 2006). The main exception is the Southwest and
parts of the interior of the West, where increased temperature has led
to rising drought trends (Groisman et al., 2004; Andreadis &
Lettenmaier, 2006).

Amazingly, Pielke’s testimony did include the second sentence about
rising drought trend in the SW and West — which would seem to render
most of his attack (and Sen. Sessions’ attack) on Holdren moot — but
Pielke buried it in a footnote. Again, Hotwhopper explains just how head-exploding this all is.

Holdren makes a key point that I have made repeatedly
— severe drought is much more than just a reduction in precipitation.
He explains: “In my recent comments about observed and projected
increases in drought in the American West, I mentioned four relatively
well understood mechanisms by which climate change can play a role in
drought. (I have always been careful to note that, scientifically, we
cannot say that climate change caused a particular drought, but only
that it is expected to increase the frequency, intensity, and duration
of drought in some regions ― and that such changes are being observed.)”

These four mechanisms are:

In a warming world, a larger fraction of total precipitation falls
in downpours, which means a larger fraction is lost to storm runoff (as
opposed to being absorbed in soil).

In mountain regions that are warming, as most are, a larger fraction
of precipitation falls as rain rather than as snow, which means lower
stream flows in spring and summer.

What snowpack there is melts earlier in a warming world, further reducing flows later in the year.

Where temperatures are higher, losses of water from soil and
reservoirs due to evaporation are likewise higher than they would
otherwise be.

Holdren reviews the scientific literature on those statements in his
reply, noting “the second, third, and fourth mechanisms reflect
elementary physics and are hardly subject to dispute (but see also
additional references provided at the end of this comment).” Holdren
states:

As I have also noted in recent public comments,
additional mechanisms have been identified by which changes in
atmospheric circulation patterns that may be a result of global warming could
be affecting droughts in the American West. There are some measurements
and some analyses suggesting that these mechanisms are operating, but
the evidence is less than conclusive, and some respectable analysts
attribute the indicated circulation changes to natural variability. The
uncertainty about these mechanisms should not be allowed to become a
distraction obscuring the more robust understandings about climate
change and regional drought summarized above.

Holdren is being characteristically conservative in his language here. As I’ve written,
climate scientists specifically predicted a decade ago that Arctic ice
loss would bring on worse droughts in the West — and California is now
in the death-grip of a brutal, record-breaking drought, driven by the
very change in the jet stream that scientists had anticipated.

But Holdren’s main point is the important one — quite separate from
any changes in precipitation that climate change may cause, there is
little dispute that human-caused climate change is worsening droughts in
the West and Southwest. I recommend his entire paper to readers interested in this important subject.